Black widows are venomous arachnids, known to be fatal to humans. However, some black widows have been misunderstood as they also rely on their webs and elaborate hunting strategies in order to hunt their prey. If you want to brush up on your black widow knowledge, here are eight fun facts about them.
They are not the world’s deadliest spider
Contrary to the Marvel comic’s claim, black widows are far from the deadliest spider on Earth. But they do have a more intimidating name than the world’s actual most-venomous spiders, Australia’s funnel-web spiders.
The Australian redback spider, a close relative of American black widows, is another contender because its venom is more potent and its bites are more common than funnel-webs. Blacks widows are the most venomous spider in North America.
Their venom is about 15 times stronger than rattlesnake venom, which uses a chemical called alpha-latrotoxin to overwhelm nerve cells and cause immense pain. When the alpha-latrotoxin reaches a person’s nerve cell, it dumps all of its signaling chemicals at once – overwhelming its neighbors.
In addition to pain, the bite can cause swelling around the wound, severe cramping, sweating and chills.But spiders are much smaller than snakes and don’t release much venom at once – so black widow bites only present high risk to young children and elderly people.
Antivenom exists for bite victims
Every year, 2,500 people seek help from poison control centers with black widow bites. The antivenom is typically prescribed only in high-risk cases or if the person has trouble breathing, high blood pressure, or is pregnant.
Antivenom was first made by pharmaceutical producers during the 1930s. To create the antivenom, large amounts of venom were injected into horses to stimulate their immune systems to produce antibodies that target chemicals in the venom.
Those antibodies neutralize the venom by flagging a person’s immune system to destroy its pain-inducing ingredients.
Not one, but many species exist
There are three types of black widows found in North America. They are the western species, Latrodectus herperus; the northern species, Latrodectus variolus; and the southern spid
The young spiders are cannibals
Spiderling cannibalism is a natural part of the eating process in female black widow spiders. But more often than not, they will eat their smaller siblings before they can get to 300 spiders. This means that when spiderlings hatch at equal size, they won’t engage in cannibalism right away.
Sexual cannibalism is surprisingly rare
Female black widows actually consume their male mates after mating. Other spider species pursue a different strategy, so scientists believe that black widows may have similar rates of cannibalism in the wild.
Male black widows also have strategies to avoid risky sexual encounters and mate with females who aren’t hungry, which researchers find prevents some males from getting eaten by female black widows.
Foreign females were observed eating domestic males after mating, but this research found that juvenile female redback spiders only ingested their mate about two percent of the time.
Tiny slits are used for “Spidey” senses
The common name of the family is Latrodectus genus, not Western Black Widow. Distinguishing features include: curved feet with bristles; earning them the nickname ‘comb-footed’; creating irregular sets of nest called tangle webs.
Enabling these spiders to move in different ways is a strange strategy: starving spiders build more sticky nets and invest more time in linking threads which may stop them from over-eating. Spiders benefit from sensing organs on their legs called slit sensilla that can tune in to certain frequencies of vibrations coming down the strands of silk.
Coloring sends a message
A human can easily figure out when they’re in danger from a female black widow’s signal of danger – the red hourglass on her belly.
But other creatures don’t always know about this sign, which is why prey and predators utilize it to stay alert. Black widows evolved with bright red spots to signal to predators that they are dangerous, but have also worked out a balance between staying hidden from their prey, and warning would-be hunters off.
Climate change is expanding their range
Black widows live across states from Florida to Massachusetts. They’re most common in the southern and southwestern US where temperatures are warm year-round. They harbor during the winter and then emerge when the weather starts to improve in springtime.